# Three-Tangle of a General Three-Qubit State in the Representation of Majorana Stars

## TL;DR

This paper extends the Majorana star representation to general three-qubit states by using SL(2,C) transformations, enabling a geometric visualization of three-tangle for non-symmetric states, which was previously limited to symmetric states.

## Contribution

It demonstrates that non-symmetric three-qubit states can be transformed into symmetric states without changing their three-tangle, allowing geometric visualization of entanglement via Majorana stars.

## Key findings

- Majorana representation can be applied to general three-qubit states after SL(2,C) transformations.
- The three-tangle remains invariant under these transformations.
- Symmetrization enables geometric visualization of entanglement for some multi-qubit states.

## Abstract

Majorana stars, the $2j$ spin coherent states that are orthogonal to a spin-$j$ state, offer a visualization of general quantum states and may disclose deep structures in quantum states and their evolutions. In particular, the genuine tripartite entanglement - the three-tangle of a symmetric three-qubit state, which can be mapped to a spin-3/2 state, is measured by the normalized product of the distance between the Majorana stars. However, the Majorana representation cannot applied to general non-symmetric $n$-qubit states. We show that after a series of SL$(2,\mathbb{C})$ transformations, non-symmetric three-qubit states can be transformed to symmetric three-qubit states, while at the same time the three-tangle is unchanged. Thus the genuine tripartite entanglement of general three-qubit states has the geometric representation of the associated Majorana stars. The symmetrization and hence the Majorana star representation of certain genuine high-order entanglement for more qubits are possible for some special states. In general cases, however, the constraints on the symmetrization may prevent the Majorana star representation of the genuine entanglement.